Polysaccharides bonded to organopolysiloxane are taught in Japanese Unexamined Patent Application Publication No. Hei 7-70204. The suggested preparation processes include, for instance, a process, in which cationized cellulose, hydroxyethyl cellulose, or chitosan are reacted with a dimethylpolysiloxane having one of the ends of the molecular chain blocked by a glycidoxypropyl group. In addition, a process, in which an isocyanate-containing organopolysiloxane is reacted with cellulose or cellulose derivatives has been offered in Japanese Unexamined Patent Application Publication No. Hei 9-136901, and a process, in which a diorganopolysiloxane having one of the ends of the molecular chain blocked by an epoxycyclohexylethyl group is reacted with a polysaccharide derivative soluble in organic solvents and containing carboxyl groups are discussed in Japanese Unexamined Patent Application Publication No. Hei 11-349601.
However, the problem with many of the above-described processes is the low ratio of organopolysiloxane introduced into the polysaccharides. This results from the low reactivity between the starting organopolysiloxane selected and the polysaccharides. While processes for isocyanate-containing organopolysiloxane can overcome this, they are disadvantageous because of the need to use toxic compounds for increased reactivity.
As a result of investigations into methods that could be used to prepare organopolysiloxane-modified polysaccharides with a high ratio of introduction of organopolysiloxane without using toxic compounds such as isocyanate-containing organopolysiloxanes, etc., the present inventors found that hydroxyl groups in polysaccharides can undergo an esterification reaction with organopolysiloxanes containing residual carboxylic anhydride groups.
Thus, the present invention provides novel polysaccharides, in which the organopolysiloxanes are bonded to the polysaccharides through ester groups, and a process for the preparation of organopolysiloxane-modified polysaccharides that permits introduction of organopolysiloxanes into polysaccharides at a high introduction ratio.